| Fusarium graminearum is one of the main pathogens of corn stalk rot in Northeast China.It is widely distributed in soil aggregates,and soil aggregates are the basic structure of soil.In this study,the distribution of Fusarium graminearum in soil aggregates of different soil strength grades was studied,and the life activities and characteristics of Fusarium graminearum were revealed.The purpose of this study is to find and control corn stalk rot in Jilin Province The method of occurrence of rot.The method of this study is to design the control group(high,medium and low soil fertility black soil in total 6 treatments are GJ,GW,ZJ,ZW)of the black soil with and without Fusarium graminearum in three experimental areas of different soil fertility levels in the central part of Jilin Province)The maize variety "jinnongda 935" was planted in the black soil with high,medium and low soil fertility,and the maize yield and disease incidence in the test area were studied According to the statistics,the soil samples were collected in autumn of 2018.The soil samples were divided into 6different particle size agglomerations(> 5mm,5-2mm,2-1mm,1-0.5mm,0.5-0.25 mm,< 0.25mm).The physical and chemical properties of the soil and the carbon and nitrogen,soil enzymes(sucrase,urease,cellulase,catalase)and the structure of soil microbial community were analyzed.Based on the study of the physicochemical properties,aggregate composition,soil enzymes and microbial community structure of the black soil with high,medium and low soil fertility and the black soil without soil fertility,the distribution characteristics of Fusarium graminearum and the differences of microbial community structure between the black soil with soil fertility and the black soil without soil fertility were studied,which provided scientific basis and number for the improvement of soil fertility and the prevention and control of soil borne diseases According to support.The results of this study mainly include the following points:(1)According to the improvement of low,medium and high soil strength,the content of macroaggregate in the black soil without Fusarium graminearum was93.7%,95.9% and 96.8% respectively,and the content of macroaggregate in the black soil with Fusarium graminearum was 92.1%,94.7% and 95.9% respectively,whichwere all increased with the increase of soil strength level,and the soil stability was significantly enhanced(P < 0.05);under the same soil strength condition,DJ’s macroaggregate was significantly increased(P < 0.05)The content of aggregates was1.6% lower than that of DW,1.2% lower than that of ZW,and 0.9% lower than that of GW in GJ.The content of soil macroaggregates decreased significantly(P < 0.05)after the introduction of Fusarium graminearum,which indicated that the stability of black soil decreased with the increase of soil fertility The influence of bacteria on the stability of black soil is weakened,which shows that the high strength black soil has strong anti-interference ability.(2)According to the improvement of low,medium and high soil strength,the content of organic carbon(SOC)in the black soil inoculated with bacteria was 8.97%,12.5% and 13.7% lower than that in the black soil inoculated with bacteria,the content of total carbon(TC)in the black soil inoculated with bacteria was 3.7%,8.0%and 8.8% lower than that in the black soil inoculated with bacteria,and the content of total nitrogen(TN)in the black soil inoculated with bacteria was 3.7%,8.0% and8.8% lower than that in the black soil inoculated with bacteria TN content decreased by 20%,15.8% and 14.8% respectively,which indicated that the content of carbon and nitrogen decreased significantly(P < 0.05),the higher the soil fertility,the higher the carbon content decreased rate,the lower the nitrogen content decreased rate;the content of organic carbon(SOC)and total carbon(TC)was the most in the small aggregates of < 0.25 mm,and the black soil with Fusarium graminearum was compared with the black soil without Fusarium graminearum The decrease rate of organic carbon content in small aggregates < 0.25 mm was higher than that in other aggregates,DJ,ZJ and GJ decreased by 9.2%,12.9% and 14.4% respectively,and the decrease rate increased with the increase of soil fertility;the total nitrogen was mainly distributed in grains > 5 mm and 2-1 mm,and the total nitrogen content in inoculated black soil was significantly lower than that in unincorporated black soil.(3)The activities of sucrase in the soil aggregates(> 5mm,5-2mm,2-1mm,1-0.5mm,0.5-0.25 mm,< 0.25mm)were decreased by 42.1%,32.7%,31%,41.4%,36.9% and 45.6% respectively compared with those in the unincorporated black soil.The activities of sucrase in the aggregates(> 5mm,5-2mm,2-1mm,1-0.5mm,0.5-0.25 mm,< 0.25mm)were decreased most obviously with the increase of soil fertility 45.6%,45.1% and 37.4% respectively,which may be due to the fact that sucrase participates in the carbon cycle in the soil,and the most obvious decrease ofsucrase activity is due to the decrease of carbon content in < 0.25 mm;the activity of urease in < 0.25 mm aggregates is higher than that in other aggregates,and the least decrease of activity after inoculation is about 25%,which may be due to the decrease of particle size of soil aggregates The content of dissolved oxygen in the soil decreased,and the anaerobic environment was built in the small aggregates,which strengthened the denitrification of the soil,and the process of soil nitrogen transformation enhanced the urease activity of the soil;The activities of cellulase and catalase in the soil were the strongest in 5-2mm aggregates.(4)With the increase of soil fertility level,the total amount of soil bacteria,fungi,actinomycetes and anaerobic bacteria increased.Fungi,bacteria,actinomycetes and Fusarium graminearum are mainly distributed in the large aggregates in the soil,and there are more in the aggregates of > 5mm,5-2mm and 2-1mm,and there are more anaerobic bacteria in the small aggregates of < 0.25 mm and 0.5-0.25 mm,which may be the distribution rule The content of Fusarium graminearum was the highest in >5mm aggregates.With the increase of soil fertility,the quantity of Fusarium graminearum had no significant change(P < 0.05).The quantity of Fusarium graminearum in the black soil with the increase of soil fertility increased more and more with the increase of soil fertility... |
